The corpus of work on the behavior and neural bases of decision making and risk assessment is growing steadily. Although much of this work within the neurosciences has focused on relatively mature human adult and non-human primate subjects, the developmental progression of risky behavior from childhood to adulthood is becoming more detailed and better characterized. The three Specific Aims of this proposal contribute to the developmental cognitive neuroscience of risky decision making by including children, adolescents, and adults, within the same paradigm, exploring individual differences and bio-markers of risk- sensitivity and risk-seeking behavior. To this end participants will engage a risky-decision making task while neural activation data are being collected. Specific Aim 1 develops a game-like task that can be used across the three populations of interest. In this paradigm, risk-seeking behavior will be determined by the tendency to select risky over safe options, and risk-sensitivity will be measured by the variability in this tendency due to the level of risk involved with these decisions. The role of numerical processing in risk evaluation will also be assessed, as will several profiles of behavior from self- and parent-report measures. Specific Aim 2 identifies the neural correlates of risk appraisal in decision-making and reward processing within age groups and individuals using functional magnetic resonance imaging (fMRI). Brain activation will be modeled by the level of risk and magnitude of values involved with a decision and its outcome, as well as the correlation between the intensity of activation in brain areas found to be sensitive to risk and individual measures of risk-sensitivity. Specific Aim 3 will ascertain the differences and similarities in behavior and neural responses to the risk and magnitude manipulations between children, adolescents, and adults, in constructing a developmental narrative. The proposed research offers a novel contribution to the study of risky decision-making through the inclusion of children and adolescents in a neuroimaging study with adults while performing identical tasks. The information gained from this study has the potential to impact health-related fields by investigating the development of brain regions integral to risk-seeking behavior, which has been linked to activities such as experimenting with drug and alcohol use, unsafe sexual practices, and hazardous driving. An understanding ofthe underlying mechanisms of such behaviors, including their development, is required if these mechanisms are to be leveraged through intervention in a time-sensitive manner.